package com.android.fxcontacts.util;

import java.lang.reflect.Array;

/**
 * ArrayUtils contains some methods that you can call to find out
 * the most efficient increments by which to grow arrays.
 */
public class ArrayUtils
{
	 private static Object[] EMPTY = new Object[0];
	    private static final int CACHE_SIZE = 73;
	    private static Object[] sCache = new Object[CACHE_SIZE];

	    private ArrayUtils() { /* cannot be instantiated */ }

	    public static int idealByteArraySize(int need) {
	        for (int i = 4; i < 32; i++)
	            if (need <= (1 << i) - 12)
	                return (1 << i) - 12;

	        return need;
	    }

	    public static int idealBooleanArraySize(int need) {
	        return idealByteArraySize(need);
	    }

	    public static int idealShortArraySize(int need) {
	        return idealByteArraySize(need * 2) / 2;
	    }

	    public static int idealCharArraySize(int need) {
	        return idealByteArraySize(need * 2) / 2;
	    }

	    public static int idealIntArraySize(int need) {
	        return idealByteArraySize(need * 4) / 4;
	    }

	    public static int idealFloatArraySize(int need) {
	        return idealByteArraySize(need * 4) / 4;
	    }

	    public static int idealObjectArraySize(int need) {
	        return idealByteArraySize(need * 4) / 4;
	    }

	    public static int idealLongArraySize(int need) {
	        return idealByteArraySize(need * 8) / 8;
	    }

	    /**
	     * Checks if the beginnings of two byte arrays are equal.
	     *
	     * @param array1 the first byte array
	     * @param array2 the second byte array
	     * @param length the number of bytes to check
	     * @return true if they're equal, false otherwise
	     */
	    public static boolean equals(byte[] array1, byte[] array2, int length) {
	        if (array1 == array2) {
	            return true;
	        }
	        if (array1 == null || array2 == null || array1.length < length || array2.length < length) {
	            return false;
	        }
	        for (int i = 0; i < length; i++) {
	            if (array1[i] != array2[i]) {
	                return false;
	            }
	        }
	        return true;
	    }

	    /**
	     * Returns an empty array of the specified type.  The intent is that
	     * it will return the same empty array every time to avoid reallocation,
	     * although this is not guaranteed.
	     */
	    public static <T> T[] emptyArray(Class<T> kind) {
	        if (kind == Object.class) {
	            return (T[]) EMPTY;
	        }

	        int bucket = ((System.identityHashCode(kind) / 8) & 0x7FFFFFFF) % CACHE_SIZE;
	        Object cache = sCache[bucket];

	        if (cache == null || cache.getClass().getComponentType() != kind) {
	            cache = Array.newInstance(kind, 0);
	            sCache[bucket] = cache;

	            // Log.e("cache", "new empty " + kind.getName() + " at " + bucket);
	        }

	        return (T[]) cache;
	    }

	    /**
	     * Checks that value is present as at least one of the elements of the array.
	     * @param array the array to check in
	     * @param value the value to check for
	     * @return true if the value is present in the array
	     */
	    public static <T> boolean contains(T[] array, T value) {
	        for (T element : array) {
	            if (element == null) {
	                if (value == null) return true;
	            } else {
	                if (value != null && element.equals(value)) return true;
	            }
	        }
	        return false;
	    }

}
